Col. Robert R. McCormick was an artillery battery commander in the 1st Battalion, 1st Infantry Division at the Battle of Cantigny in the Great War, May, 28, 1918
The formal name of the Post is First Division Cantigny Post 556.
A history of the Colonel and the Posts he supported.

Col. Robert R. McCormick was a very powerful patron of both Posts 348 (initially, Medill-Tribune and after his death, eponymous) and 556 and of the Society of the First Division (Cantigny Chapter). By encouragement of joint membership of the Society of the First Division Cantigny Chapter and of Post 556, he encouraged the early growth of the post.

We are a doing Post, not a sit around and talk Post. We raise about $20,000 a year in support of the Midwest Shelter for Homeless Veterans here in Wheaton, Illinois, and support several Americanism programs through pancake breakfasts, pasta dinners, collections at many Cantigny Park and Golf events and Memorial Day weekend Poppy distribution.